The purpose is to gauge as to how quickly you can think. There are 50 questions, and no one gets a perfect score. I took several prep tests, and realized that it is best to guess at any question that you cant figure out in 10 seconds. They also give you multiple tries if you do fail. Proud to say that i passed with score above 80%. Would have scored higher if i just skipped the math questions, as the last 3 were spatial.